How IsiZulu speakers use cohesion in English in their academic writing

A research report submitted to the Wits School of Education, Faculty of Humanities, University of the Witwatersrand in partial fulfillment of the requirements for the degree of Master of Arts by combination of coursework and research. Johannesburg, 2015Achievement rates in higher education in South Africa for black students remain low after 20 years of democracy. Writing academic English according to existing conventions is a complex skill. One aspect of this skill is producing dense, cohesive text. The writing of a group of IsiZulu speakers at Wits is analyzed to find out how Hallidayan (1976) cohesion is operating therein: how does this language group use conjunctions, lexical cohesion, referencing, ellipsis and substitution when writing in English? In addition, it explores whether differences in how IsiZulu and English are structured create problems with cohesion for these undergraduates when writing in English. Furthermore, it aims to uncover if the rhetorical structure of IsiZulu influences the organization and the cohesion of their English texts. From this analysis, it is evident that there are elements of referencing, conjunction use and lexical cohesion which are well developed in their writing. At the same time, evidence of speech-type syntax in the data points to areas where further development is possible. This knowledge has led to suggestions on how academic literacy input could facilitate writing skills development for this language group. The investigation has also established the dominance of English rhetorical organisation in both the English and IsiZulu writing of this cohort. It has also shown that these students experience rhetorical conflict when instructed not to use repetition as a meaning-making strategy in their writing. Both a pragmatic and a critical response to these findings has been provided. The pragmatic response is a set of suggestions on how to develop language skills in the area of cohesion. The critical response is a proposal for an alternative style of academic textual organisation with stronger links to IsiZulu oral rhetoric practices. Key words: Cohesion in IsiZulu, cohesion in English, IsiZulu rhetoric, English rhetoric, academic literacy, transformation in tertiary educatio

Technology development of 3-S GaAs radiation detectors

A novel type of GaAs radiation detector featuring a three-dimensional array of electrodes that penetrate through the detector bulk is described. The development of the technology to fabricate such a detector is presented along with electrical and radiation source tests. Simulations of the electrical characteristics are given for detectors of various dimensions. Laser drilling was used to create holes in the detector bulk. Two types of laser were investigated: Nd:YAG and Ti: Sapphire. The Nd:YAG laser produced repeatable round holes of 30 mum diameter with little or no taper and smooth internal walls. The Ti:Sapphire laser produced holes of 100 mum diameter with very little ejected debris. Electrodes were formed within the holes by metal evaporation, creating diode cells with a Schottky-Schottky configuration. Two types of cell were fabricated: three-electrode and nine-electrode. The cells had 60 mum diameter holes with a 210 mum pitch. Electrical measurements made on both cells revealed characteristics with low leakage currents and high breakdown voltages. The three-electrode cell had a reverse breakdown voltage of approximately 100 V and a reverse leakage current of approximately 20 nA while the nine-electrode cell had a reverse breakdown voltage of approximately 500 V and a reverse leakage current of approximately 5 nA. Forward and reverse bias I-V measurements showed asymmetrical characteristics, which are not seen in planar diodes. Energy spectra were obtained using 5.45 MeV alpha particles and 60 keV photons. The alpha source measurements produced a charge collection efficiency of 50%. Simulations of a nine-electrode cell with identical dimensions to the fabricated cell were performed. The results showed asymmetrical forward and reverse bias I-V characteristics, similar to those found experimentally. The simulated I-V characteristics also showed a breakdown voltage of 500 V with low leakage currents, consistent with those found experimentally. The simulations showed that the cell is not fully depleted at 500 V. Simulations of a nine-electrode cell with 10 mum electrodes with a 25 mum pitch were also performed. The I-V characteristics again showed a high breakdown voltage with a low leakage current but also showed a full depletion voltage of just 8 V

How isiZulu speakers use cohesion in their academic writing in English

Achievement rates for black students in South African higher education remain low after 20 years of democracy. Writing academic English according to existing conventions is a complex skill. One aspect of this skill is producing cohesive text. In this article, the writing of a group of isiZulu speakers at Wits is analysed to determine how Hallidayan cohesion is operating therein: how does this language group use conjunctions, lexical cohesion, referencing, ellipsis and substitution when writing in English? From this analysis, it is evident that there are elements of referencing, conjunction use and lexical cohesion which are well developed in their writing. At the same time, evidence of speech-type syntax in the data indicates areas where further development is possible. These findings have led to suggestions on how academic language input could facilitate writing skills development for this language group

Development of MPC-DPA polymeric nanoparticle systems for inhalation drug delivery applications

Inhalation of nanoparticles for pulmonary drug delivery offers the potential to harness nanomedicine formulations of emerging therapeutics, such as curcumin, for treatment of lung cancer. Biocompatible nanoparticles composed of poly(2-methacryloyloxyethyl phosphorylcholine)-b-poly(2-(diisopropylamino)ethyl methacrylate) (MPC-DPA) have been shown to be suitable nanocarriers for drugs, whilst N-trimethyl chitosan chloride (TMC) coating of nanoparticles has been reported to further enhance their cellular delivery efficacy; the combination of the two has not been previously investigated. Development of effective systems requires the predictable, controllable, and reproducible ability to prepare nanosystems possessing particle sizes, and drug loading capacities, appropriate for successful airway travel, lung tissue penetration, and tumour suppression. Although a number of MPC-DPA based nanosystems have been described, a complete understanding of parameters controlling nanoparticle formation, size, and morphology has not been reported; in particular the effects of differing solvents phases remains unclear. In this current study a matrix of 31 solvent combinations were examined to provide novel data pertaining to the formation of MPC-DPA nanoparticles, and in doing so afforded the selection of systems with particle sizes appropriate for pulmonary delivery applications to be loaded with curcumin, and coated with TMC. This paper presents the first report of novel data detailing the successful preparation, characterisation, and optimisation of MPC-DPA nanoparticles of circa 150 – 180 nm diameter, with low polydispersity, and a curcumin loading range of circa 2.5 – 115 µM, tunable by preparation parameters, with and without TMC coating, and thus considered suitable candidates for inhalation drug delivery applications

Exosomes containing HIV protein Nef reorganize lipid rafts potentiating inflammatory response in bystander cells.

HIV infection has a profound effect on "bystander" cells causing metabolic co-morbidities. This may be mediated by exosomes secreted by HIV-infected cells and containing viral factors. Here we show that exosomes containing HIV-1 protein Nef (exNef) are rapidly taken up by macrophages releasing Nef into the cell interior. This caused down-regulation of ABCA1, reduction of cholesterol efflux and sharp elevation of the abundance of lipid rafts through reduced activation of small GTPase Cdc42 and decreased actin polymerization. Changes in rafts led to re-localization of TLR4 and TREM-1 to rafts, phosphorylation of ERK1/2, activation of NLRP3 inflammasome, and increased secretion of pro-inflammatory cytokines. The effects of exNef on lipid rafts and on inflammation were reversed by overexpression of a constitutively active mutant of Cdc42. Similar effects were observed in macrophages treated with exosomes produced by HIV-infected cells or isolated from plasma of HIV-infected subjects, but not with exosomes from cells and subjects infected with ΔNef-HIV or uninfected subjects. Mice injected with exNef exhibited monocytosis, reduced ABCA1 in macrophages, increased raft abundance in monocytes and augmented inflammation. Thus, Nef-containing exosomes potentiated pro-inflammatory response by inducing changes in cholesterol metabolism and reorganizing lipid rafts. These mechanisms may contribute to HIV-associated metabolic co-morbidities

Lipid metabolism in patients infected with Nef-deficient HIV-1 strain

Background: HIV protein Nef plays a key role in impairing cholesterol metabolism in both HIV infected and bystander cells. The existence of a small cohort of patients infected with Nef-deficient strain of HIV presented a unique opportunity to test the effect of Nef on lipid metabolism in a clinical setting. Methods: Here we report the results of a study comparing six patients infected with Nef-deficient strain of HIV (Delta NefHIV) with six treatment-naive patients infected with wild-type HIV (WT HIV). Lipoprotein profile, size and functionality of high density lipoprotein (HDL) particles as well as lipidomic and microRNA profiles of patient plasma were analyzed. Results: We found that patients infected with Delta NefHIV had lower proportion of subjects with plasma HDL-C levels < 1 mmol/l compared to patients infected with WT HIV. Furthermore, compared to a reference group of HIV-negative subjects, there was higher abundance of smaller under-lipidated HDL particles in plasma of patients infected with WT HIV, but not in those infected with Delta NefHIV. Lipidomic analysis of plasma revealed differences in abundance of phosphatidylserine and sphingolipids between patients infected with Delta NefHIV and WT HIV. MicroRNA profiling revealed that plasma abundance of 24 miRNAs, many of those involved in regulation of lipid metabolism, was differentially regulated by WT HIV and Delta NefHIV. Conclusion: Our findings are consistent with HIV protein Nef playing a significant role in pathogenesis of lipid-related metabolic complications of HIV disease

Development of geopolymer mortar under ambient temperature for in situ applications

Geopolymer concrete technology involves production of more environmentally friendly waste material-based concrete which could be a viable solution for conventional concrete replacement. Typical fly ash-based geopolymer concrete however requires high temperature curing treatment in order to develop sufficient early strength properties, which is considered a severe limitation for cast-in-place concrete applications. Most previous studies on geopolymer concrete have focused on the properties of concretes pre-hardened by heat curing and/or by aggressive chemical treatment (e.g. alkali activation using concentrated sodium hydroxide (NaOH)). The current study presents an extensive experimental investigation on the mechanical and microstructural properties of geopolymer concrete mixes prepared with a combination of fly ash and slag cured under ambient temperature. ‘User friendly’ geopolymer mixes were produced using fly ash (FA) and Ground Granulated Blast furnace Slag (GGBS) mixed together with potassium silicate with molar ratio equal to 1.2 (as the activator) and water. The results indicated that heat curing treatment can be avoided by partial replacement of fly ash with slag. The compressive strength of the examined mixes was found to be in the range of 40–50 MPa for 40% and 50% GGBS replacement mixtures respectively. Moreover, the flexural and direct tensile strengths of geopolymer mixes are considerably improved as the GGBS content is increased. Based on FTIR and SEM/EDS analysis, the inclusion of a higher content of GGBS resulted in a denser structure by formation of more hydration products

Lipid metabolism in patients infected with Nef-deficient HIV-1 strain.

BACKGROUND: HIV protein Nef plays a key role in impairing cholesterol metabolism in both HIV infected and bystander cells. The existence of a small cohort of patients infected with Nef-deficient strain of HIV presented a unique opportunity to test the effect of Nef on lipid metabolism in a clinical setting. METHODS: Here we report the results of a study comparing six patients infected with Nef-deficient strain of HIV (ΔNefHIV) with six treatment-naïve patients infected with wild-type HIV (WT HIV). Lipoprotein profile, size and functionality of high density lipoprotein (HDL) particles as well as lipidomic and microRNA profiles of patient plasma were analyzed. RESULTS: We found that patients infected with ΔNefHIV had lower proportion of subjects with plasma HDL-C levels/l compared to patients infected with WT HIV. Furthermore, compared to a reference group of HIV-negative subjects, there was higher abundance of smaller under-lipidated HDL particles in plasma of patients infected with WT HIV, but not in those infected with ΔNefHIV. Lipidomic analysis of plasma revealed differences in abundance of phosphatidylserine and sphingolipids between patients infected with ΔNefHIV and WT HIV. MicroRNA profiling revealed that plasma abundance of 24 miRNAs, many of those involved in regulation of lipid metabolism, was differentially regulated by WT HIV and ΔNefHIV. CONCLUSION: Our findings are consistent with HIV protein Nef playing a significant role in pathogenesis of lipid-related metabolic complications of HIV disease

Zebrafish embryonic lipidomic analysis reveals that the yolk cell as metabolically active in processing lipid

The role of lipids in providing energy and structural cellular components during vertebrate development is poorly understood. To elucidate these roles further, we visualized lipid deposition and examined expression of key lipid-regulating genes during zebrafish embryogenesis. We also conducted a semiquantitative analysis of lipidomic composition using liquid chromatography (LC)-mass spectrometry. Finally, we analyzed processing of boron-dipyrromethene (BODIPY) lipid analogs injected into the yolk using thin layer chromatography. Our data reveal that the most abundant lipids in the embryo are cholesterol, phosphatidylcholine, and triglyceride. Moreover, we demonstrate that lipids are processed within the yolk prior to mobilization to the embryonic body. Our data identify a metabolically active yolk and body resulting in a dynamic lipid composition. This provides a foundation for studying lipid biology during normal or pharmacologically compromised embryogenesis

Prion infection impairs cholesterol metabolism in neuronal cells

Conversion of prion protein (PrPC) into a pathological isoform (PrPSc) during prion infection occurs in lipid rafts and is dependent on cholesterol. Here, we show that prion infection increases the abundance of cholesterol transporter, ATP-binding cassette transporter type A1 (ATP-binding cassette transporter type A1), but reduces cholesterol efflux from neuronal cells leading to the accumulation of cellular cholesterol. Increased abundance of ABCA1 in prion disease was confirmed in prion-infected mice. Mechanistically, conversion of PrPC to the pathological isoform led to PrPSc accumulation in rafts, displacement of ABCA1 from rafts and the cell surface, and enhanced internalization of ABCA1. These effects were abolished with reversal of prion infection or by loading cells with cholesterol. Stimulation of ABCA1 expression with liver X receptor agonist or overexpression of heterologous ABCA1 reduced the conversion of prion protein into the pathological form upon infection. These findings demonstrate a reciprocal connection between prion infection and cellular cholesterol metabolism, which plays an important role in the pathogenesis of prion infection in neuronal cells